In fact, it's his sciatica playing up, but the man who's one of Australia's longest-serving store Santas has a fast answer for every tricky question.

For 50 years, jolly Mr Jones in his Santa alter-ego has been the best thing about Saturday morning shopping for countless thousands of kids with his many store appearances in Mount Gambier and Adelaide.

Just 14 years old when he first donned the famous red suit in 1964, his first gig was handing out free milkshakes to customers coming in the door at a Mount Gambier general store.

"I've always been a stocky lad," he says, tapping a hand on his sizeable belly.

Since then, Mr Jones has been dropped in by helicopter to appear at Christmas parades, shown up at old folks homes, and even been hired by eager mums and dads to wake up sleepy kids in the early hours of Christmas morning.

"It's magical mystery, isn't it? I think you have to do your job properly or not do it at all," he declares.

Disappearing Clark Kent style into the bathroom with a suitcase, he emerges 20 minutes later as Santa Claus, complete with a 'custom-made-for-Lou' suit.

Made of crushed red velvet with fluffy white trim and with a flowing realistic beard, it's one of around 10 he's got in the closet at home.

A vest worn underneath soaks up any 'Santa smell' that sitting prone on a throne for three hours might create and his beard gets replaced annually, depending on how many children have used it as a handy handkerchief.

Those pesky 'Santa moments'

Bodily fluids are an occupational hazard, says Mr Jones.

He's been pooped and vomited on and has seen more than his fair share of boogers, delivered by a wandering finger or sneeze.

Although the parents are often horrified, Mr Jones just tells them it's a 'Santa moment'.

"I just laugh it off, go off to 'feed the reindeers' and wipe it all off," he said.

Mr Jones reckons he can win over nine out of 10 children, but experience has taught him how to deal with a quivering bottom lip and a refusal to let go of mum's legs.

"The reason why they're upset is because mum and dad have said 'Santa won't come this year' or 'you won't get as many presents this year'," he said.

"They're all excited to see Santa, but by the time they come in the store they don't want to see me or scream and carry on.

"I'm pretty scary-looking - I mean what person walks around looking like this all day?" jokes Mr Jones.

But years of watching the body language of children has taught him a few simple secrets about turning a frown upside-down.

High-fives, eye contact and talking to them as a friend are his tricks of the trade.

"I had one child last weekend whose dad I knew and he said 'Lou if you can convince him, you are the best Santa'," he said.

"This kid was screaming. Within five seconds, I had him sitting beside me."

His lightning-fast wit often helps when it comes to tricky questions drilled CIA-style by a two-year-old with parents listening nearby.

One of the questions he's asked most is 'how do you get around every part of the world in one night?'

A quick explanation of the International Date Line and how it allows him to have two Christmases, one day after the other, gets him out of trouble.

To the child that asks him where Rudolph is, he says, 'Rudolph only comes out on a foggy night'.

Present requests are slightly more difficult.

"I had a young kid come up the other day, about five or six and I said 'what do you want for Christmas?' and he said 'a million dollars'.

"I said to his mum, 'take X-Lotto out, you never know, you might win it'."

His own children, aged 17, 13 and five, have clued him up as to the latest toys and gadgets a knowledgeable Santa needs to deal with gift requests, although there's still a mild generational gap.

"A 'wee' to me is when you used to go to the toilet - now I hear they have a Wii in boxes," he said.

'It's just seeing the faces of the children'

But times have changed dramatically since Lou began, with store Santas across Australia now having to adhere to some stringent regulations and bow to political correctness.

In the requisite training, wannabe Santas learn the right way to deliver the trademark merry laugh, the 'ho ho ho' being replaced by a 'ha ha ha'.

Everyone must have a working with children check and kids are no longer allowed to perch on Santa's knee, but are required to sit beside him.

"The only ones I hold are babies up until about nine months," said Mr Jones.

Both his hands have to be on show while a child is with him and cuddling is still okay, but Mr Jones has to angle his body away from the children.

Mr Jones said the changes are sad but necessary, designed to protect both parties.

Every once in a while, deep in Santa's confidence, a child will look him in the eye and ask for wishes that make him tear up and have to leave his post to recover.

"I've had some children come up and ask me to tell [their] Dad stop to hitting his Mum," said Mr Jones.

"That's when I go off to feed the reindeer. It's very sad."

But Mr Jones said all the preparation and hard work is worth it when he sits down and sees an excited kid making a bee-line in his direction dragging a parent along in their wake.

Indeed, watching him in action as he deftly turns a crying three-year-old Lily into a smiling bubbly little girl is akin to watching a master at work.

"Just seeing the faces of the children, some will run to you, give you a high-five, wave to you, it's just seeing their faces," he said.

"It's this moment you get with them, to make them very happy - that's important."